Cultural histories of body parts are all the rage. Fashions, beliefs and fetishes have been catalogued on everything from hair to navels, thumbs to toes, and all the fun bits between. Histories of the genitals – a small industry in themselves – tend to have the most tittering titles: no prize for guessing what A Mind of Its Own, Read My Lips or The Rear View are about.

Breasts, in art as in life, are also a popular object of meditation. But cultural histories of the human mammary gland – sketches of saints and a long march through the annals of European art – are rarely as titillating as readers might wish.

And herein lies Florence Williams’ point of departure in Breasts: A Natural and Unnatural History. Williams leaves St Agatha’s breasts to wobble on a platter in the Louvre and turns to science to ask the ontological question of our age: Why is there something rather than nothing?

More specifically – and converse to the cry of tweenie angst – why are there breasts rather than no breasts? Or why was Jayne Mansfield (“a 41-inch bust and a lot of perseverance will get you more than a cup of coffee – a lot more”) Jayne Mansfield?

Given that female humans are the only mammals to sport year-round breasts, regardless of reproductive status, it is a curious question. In the early 14th century, a surgeon to the king of France proposed, among other quaintnesses, that breasts existed to warm and strengthen the stomach. In 1840, a more forbidding physician speculated that fatty breasts “enable women of the lower class to bear the very severe blows which they often receive in their drunken pugilistic contests”.

In delivering a more sensible answer, Williams, an American journalist and writer, has a prominent anthropologist to slay: cue Desmond Morris, author of The Naked Ape.

The human shift to bipedalism had many advantages – it freed the hands, for one – but the loss of male “hindsight” that came from face-to-face sex was not, apparently, chief among them. The reason women have breasts, Morris informs us, is because our cave-dwelling forefathers preferred the fronts of our cave-dwelling foremothers to mimic their backs: “The protuberant, hemispherical breasts of the female,” Morris deadpans, “must surely be copies of the fleshy buttocks, and the sharply defined red lips around the mouth must be copies of the red labia.”

(From which we may deduce that lips on men, if they be red, must surely be a most serious case of false advertising.)

The peculiar idea that men bred breasts in women out of a desire for front-buttocks went uncontested until, mercifully, someone cried bollocks. Breasts, Welsh writer Elaine Morgan argued in The Descent of Woman (1972), do owe something of their existence to bipedalism, but not for the reasons Morris supposes. The pendulous shape of the breast and its marvellous manoeuvrability – in humans the nipple is not anchored tightly to the ribs as it is in monkeys – allows a baby to feed while held in the crook of its upright mother’s arm.

If men are turned on by the resulting contours (and it must be acknowledged that across cultures not all are) it is not as architects of the breast but as beneficiaries of the infant’s – as Darwin put it – “struggle for existence”.

But Morgan’s argument, however sensible, has not dampened female efforts to exploit male infatuation with mammary glands. In the past century, women have lined up to inflate their breasts with everything from glass balls to ivory, paraffin wax to wood chips, peanut oil to honey, and goat’s milk to ox cartilage.

In 1962 the first silicone implant surgery took place in Texas, but less well-heeled women settled for silicone injections. In 1964 a topless go-go dancer had 44 such injections and made her fortune as “the new Twin Peaks of San Francisco”. Tom Wolfe immortalised her anatomy in The Pump House Gang (1968):

Carol Doda’s breasts are two incredible mammiform protrusions, no mere pliable mass of feminine tissues and fats there but living arterial sculpture – viscera spigot – great blown-up aureate morning-glories.

It’s hard to imagine, but these days there are more worrying things going into breasts than implants, and this is where Williams’ fascinating book turns deadly serious.

Breasts, it turns out, are not only receptacles for fantasy but also mirrors of our industrial lives, as Williams learned when she sent her breast milk to Germany for chemical testing. Her levels of flame-retardants came back 10 to 100 times higher than for European women, and she tested positive for perchlorate – a jet-fuel ingredient – and pesticides. These chemicals, deriving from household items – sofas, toys, electronics, play a dicey game with female and male estrogen levels. Against this backdrop, the human breast is un-gendered – a breast is a breast is a breast – and men are advised to ignore the lure of female breasts and pay attention to their own.

Welcome

Bronwyn Lea is the author of four books of poems: Flight Animals; The Wooden Cat and Other Poems; The Other Way Out; and most recently The Deep North: A Selection of Poems published by George Braziller Inc. in 2013. Her poems are widely anthologised, appearing most recently in Thirty Australian Poets, Australian Poetry Since 1788, Sixty Classic Australian Poems, and The Penguin Anthology of Australian Poetry.

As Poetry Editor at the University of Queensland Press her list included award-winning titles by Australia’s most distinguished poets – David Malouf, John Tranter, Laurie Duggan, John Kinsella, and many others.

Bronwyn reviews poetry, fiction and non-fiction for a number of literary pages, and she is a Politics and Society columnist at The Conversation.

She lives in Brisbane and teaches literature and writing at the University of Queensland.